1. Field of the Invention
The present invention relates to a method for manufacturing a ratchet type ring spanner having a larger cavity for receiving a larger pawl.
2. Description of the Related Art
Ring spanners can be used in a limited space, e.g., an engine room of a vehicle, as they have a small-size head when compared with other kinds of wrenches. Ratchet type ring spanners have been developed to overcome the problem of insufficient torque-bearing capacity, which largely depends on the size of the pawl. FIGS. 8A and 8B of the drawings illustrate formation of a conventional ratchet type ring spanner by means of placing a T-shaped milling cutter 6 in a hole 2 in the head 9 and then moving the T-shaped milling cutter 6 toward the handle 1, thereby forming a cavity 3 in a web between the head 9 and the handle 1. However, the size of the cavity 3 thus formed is limited, as the shaft 7 of the T-shaped cutter 6 is restrained by an inner periphery defining the hole 2 of the head 9. Namely, the cavity 3 is relatively shallow and thus only capable of receiving a pawl 4 having a relatively small thickness. As a result, the pawl 4 that engages with a drive wheel 5 (FIG. 9) rotatably received in the hole 2 of the head 9 for driving fasteners cannot provide a high torque-bearing capacity.
In addition, as illustrated in FIG. 9, the pawl 4 is pressed against a wall defining the cavity 3 at a point 8 that is relatively away from a center of the wall defining the cavity 3. Typically, the pressing point 8 approximately corresponds to the position of the third tooth of the pawl 4 counting from an adjacent end of the pawl 4. There is no support for the inner lateral side of the pawl 4 facing away from the drive wheel 5. Thus, no reactive force is obtained when the pawl 4 is subjected to a force greater than a critical value. The other lateral side of the pawl 4 facing the drive wheel 5 pivots about the pressing point 8 and slightly disengages from the teeth of the drive wheel 5. As a result, a seesaw effect is incurred on the pawl 4 which leads to a poor engagement between the pawl 4 and the drive wheel 5; namely, the pawl 4 merely engages with the drive wheel 5 by the first three teeth, which tends to cause damage to these three teeth. A solution to increase the torque-bearing capacity is to increase the size of the pawl 4, yet this contradicts the advantage of ring spanners for use in limited spaces, as the size of the head 9 is also increased.
An object of the present invention is to provide a method for manufacturing a ratchet type ring spanner having a larger cavity for receiving a larger pawl.
In accordance with the present invention, a method for manufacturing a ratchet type ring spanner having a larger cavity in a handle thereof for receiving a larger pawl comprises the steps of:
providing a ring spanner having a handle and a head extending from the handle, the head having a hole defined therein;
forming a cutout on a face of the handle, the cutout being communicated with the hole of the head;
placing a cutter in the hole of the head; and
moving the cutter toward the handle until a shaft of the cutter is stopped by a periphery defining the cutout, thereby forming a cavity in the handle.
The cavity thus formed is larger than that formed by conventional methods. Thus, a larger pawl can be received in the larger cavity, which, in turn, increases the overall torque-bearing capacity of the ratchet type ring spanner.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.